1. Cellular
and Molecular Biology Graduate Program,‡Single Molecule Analysis Group, §Department of Biomedical
Engineering, ∥Michigan Nanotechnology Institute for Medicine and Biological Sciences, ⊥Department of Internal
Medicine, #Life
Sciences Institute, ○Department of Mechanical Engineering, □Department of Chemical Engineering, and ΔDepartment of
Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States